Addition
6+6=
Upside-down Pretzel
1+1=
Window
1+3+1+3=
Dead 8
7+7=
Upside-down triangle (Turn it around Illuminati)
2+2=
Fish
1+2+1+2=
Dead Fish
8+8=
Circle squared
3+3=
8
2+1=
Half of a fish
9+9=
Pretzel
4+4=
Trident
H2O+H2O=
Ho Ho Ho Ho it's Santa Claus
10+10=
Power on power off
5+5=
Upside-down fish
1+1+1+1
Addition